Among the biggest users of land mobile two way radio systems are the members of the Association of Public-Safety Communications Officials-International, Inc. (APCO). APCO includes state and local government employees involved in the management, design, and operation of police, fire, emergency medical, local government, highway maintenance, forestry conservation, disaster relief and other public safety communications systems.
Land mobile two way radio systems include analog communication systems and digital communication systems. In addition, radio systems may be described as conventional or trunked systems, each having a wide variety of different standards or protocols, many of which operate using manufacturer specific proprietary protocols.
This varied landscape of radio systems has created problems that have been identified by APCO and other radio users and system administrators. For example, local emergency medical service providers may encounter radio communication problems when faced with multiple emergency situations. Multiple emergencies occurring at geographically different locations of a city may lead to confusion and unnecessary delay which can result in life-threatening consequences for victims as well as responders. In addition, major natural disasters such as hurricanes, earthquakes, and floods are typically handled by several different public safety agencies where the ability to communicate between agencies is a necessity. Using current two way radio technology, responding rescue personnel from federal, state, and local public safety agencies may discover that coordinating their rescue efforts is difficult because the radios from the different agencies each may use different frequencies and signaling techniques. It has been reported that some on-scene commanders have been forced to borrow radios from one another to coordinate their emergency crew activities. In some cases, the radio systems are unable to communicate with each other.
APCO, with support from the U.S. Telecommunications Industry Association (TIA), has set forth Project 25 (P25) to address the interoperability shortcomings of land mobile two way radio systems. Radio equipment manufacturers have been instrumental in developing the standards adopted by the P25 steering committee.
What is needed is a system and method that meets the interoperability standards of APCO P25, and yet allows a caller to quickly and reliably establish a multicast group, communicate a radio message to the selected group, and then allow those same recipients to further establish and communicate in yet other multicast groups.